This invention is a method of and an apparatus for teaching and learning the techniques for bowing stringed instruments. In particular, it is a method of and an apparatus for performing the following functions. It detects one or more bowing point positions on a bow and on the strings of the stringed instrument, determines the velocity of the bow, determines the bowing force and processes that information in a computer to provide real-time feedback to a student or other user of the bow on the stringed instrument. The invention may also provide comparisons for the student of his or her technique with that of a teacher or any model to enable the student to make technical changes to achieve a better tone.
Traditional ways of teaching the playing of the violin and other bowed stringed instruments rely on the teacher to convey what is required of the student. It is predicated on the subjective requirement that the student learn the various methods as perceived by the teacher. This teaching approach has shortcomings. Sound is abstract; the teacher's relation of tone by the verbal-and-demonstration approach may not be fully understood by the student. A teacher, and in particular a good teacher, may also not be available to help the student solve problems in tone production. A tool to assist the teacher in filling the communication gap and in augmenting the human teacher's efforts would be very useful.
Tone production is a critical element in violin playing. Tone quality is often the primary criterion used to differentiate an accomplished or professional violinist from an amateur or unskilled one. Many theories have been formulated on the subject of violin playing. However, the technique of producing good tone remains one of the most difficult skills that advanced violinists have to master.
In general, good tone production is dependent mostly upon good bow control. Violinists exert subtle control over their instruments and bows to produce the sounds they desire, and it is in the area of tone production that most difficulties arise. A teacher always wants a student to play in a certain way to produce a certain tone that the teacher desires. The teacher is therefore constantly trying to contrast the differences in tone produced by the teacher and that produced by the student, hoping to minimize those differences.
Many violin teachers try to communicate their concepts of tone through verbal description, demonstration or both. However, verbal descriptions of tone quality are often inadequate to convey understanding to a student. The experience of each person is different, and so his or her perceptions differ from those of others. To explain verbally how a tone should sound is too limiting.
Demonstration of tone quality by the teacher is another technique that is often used to teach tone quality. It relies very much on the ability of the student to imitate or emulate the teacher. However, having a good teacher as a model is often a matter of luck. And even if a student is able to study with a good model teacher, the student may not be able to keep up with the requirements set by that teacher for various reasons. The teacher may require that a certain amount of work be done within a given time period, but the student may not be able to do the work in time. Should the student fall behind, he or she may not be able to catch up easily or at all. A void that needs to be filled may arise, one that, when filled, will help the student violinist a great deal.
Technology in recent years has had a revolutionary impact on the music profession. The computer has been extensively used in Computer-Assisted Instruction and Computer-Based Training in music. These new trends have helped music students acquire musical skill and knowledge in a variety of areas ranging from drill-and-practice ear training to open-ended programs of musical composition. However, most of the applications involving computers have used synthesized sound sources. It would be useful to have a system for monitoring as many as four of the key parameters relating to the hand holding the bow that affect tone production on stringed instruments. The four parameters are bow position, bow pressure, bow velocity, and sounding point, the place on the string where the bow contacts the string. The four parameters offer various combinations which represent a large number of possibilities.
In order to improve playing technique, a systematic evaluation of the variables would be very helpful to students of the violin and other bowed stringed instruments such as the viola, cello, bass viol, the hwu-chyn family, a group of bowed Chinese stringed instruments, and the like. This would help students to learn with or without a teacher present. Such a system would further help students understand how a tone is produced. Based on the system's analytical results of the parameters, students will be able to make final adjustments after viewing data so obtained. Mechanical adjustments are involved; however, they are made based on interpreting the parameter data. Likewise, using this system would allow a teacher or a student to focus on the parameters of bow movement themselves rather than on the physical mechanics of body or finger movements. The students would then be better able to attain an improved tone on a stringed instrument.
Producing a desirable tone has traditionally been the most critical phase in learning to play a stringed instrument, especially a violin. Previous efforts at improving tone production on the violin fall into two categories, described here as the traditional approach and the technology-based method. Until very recently, most efforts in violin pedagogy had relied on following the recommendations of master performers serving as teachers. In Violin Playing As I Teach It, Leopold Auer in 1921 defined "an entirely agreeable tone" as "a tone which is singing to a degree that leads the hearer to forget the physical process of its development." This abstract concept may mean different things to different students. For guidance in this regard, Auer wrote, "The students must rely upon the precepts of the great masters of the past and the great violinists of the present day." Auer concluded that clear and complete understanding, the gift of seizing and retaining the explanations of a good teacher, is the only practical way of achieving a beautiful tone. Auer in his book described the violin teaching of his teacher, Joachim, who, without much elaboration, required his students to listen and imitate his playing. Joachim theorized that verbal communication is unnecessary in teaching. Auer therefore contended that "teaching without demonstration" is "dumb teaching." These two violin masters belonged to the school believing the teacher, who is in the position to demonstrate, to be the ultimate learning model for the student.
In contrast, other more recent violin pedagogues have used a more scientific approach to violin tone production. In her many publications, such as A New Approach To Violin Playing, 10th Edition, originally published in 1961, the renowned violin teacher Kato Havas in 1988 further expounded on the definition of sound. She cited some of the many writings of Leslie Taylor, who described tone quality in his Teachers' Training Course as follows. "What is very remarkable about the harmonics series is that the timbre of an instrument depends on the presence or absence, or relative strength or weakness, of the various harmonics." Havas also notes that the quality of a musical sound depends not only on the fundamental note but also on its harmonics. She essentially emphasized that to hear the various mixtures of harmonics and to exercise good control of the base joints of the left hand and the right arm in the case of right-handed violinists are critical to the production of good tone. This also emphasizes the role of coordination between the right and left hands in solving the problems of tone production.
Percival Hodgson in 1934 studied violin bowing problems from the anatomical aspect as well as the acoustical, mechanical and geometrical aspects. In his Motion Study and Violin Bowing, American String Teachers Association, 1934 (1958), he tried to solve the problems of bowing by means of scientific motion studies. Compared to the so-called "elbow, wrist, . . . " schools, it is an advanced approach to the study of violin bowing. However, before a violin student reaches the advanced stage in his or her studies, too much emphasis on physical motion may mislead that student into giving priority to the control of motion itself instead of to the production of a desired tone.
The well-known violin teacher Ivan Galamian in 1962 wrote a great deal on the subject of tone production. In his Principles of Violin Playing & Teaching, Prentice-Hall, N.J., 1962, he theorized that good tone production is dependent upon two factors, the flexible springlike action of the arm and bow, and the motion of the stroke at substantially a right angle to the long dimension of the string. There are three fundamental factors involved in the motion of the bow stroke, according to Galamian at page 55:
(1) the speed of the bow stroke; PA1 (2) the pressure exerted by the bow on the strings; and PA1 (3) the location of the sounding point, the point at which the bow contacts the string. PA1 1. Bow position was measured by embedded a piece of resistive wire in the bow hair while the violin strings were connected to the ground of an external Wheatstone bridge. The bridge was adjusted to balance when the middle part of the bow was in contact with the string. Hence, other bow positions gave positive or negative signals accordingly. PA1 2. Bow velocity was obtained by differentiating the bow position signals with respect to time. PA1 3. Bow pressure was obtained by mounting sensors for bow force, comprising four strain gauges, on bronze strips through which the bow hairs were fastened to the bow. These gauges were connected to a second Wheatstone bridge.
These three factors are interdependent in that a change in any one of them will require a corresponding adjustment in at least one of the others. When change occurs in all three factors, a great number of combinations can result, according to Galamian. This theory gives us a more rational direction in the search for proper ways to attain a desirable tone, even though it may not be easy for the violin student to grasp. This is because applying the theory may involve many different combinations of the parameters. The violin student may not have the ability to master certain parameter combinations at any given stage of his or her development.
In view of all these speculative theories, there have been some prior studies on how such parameters affect the sound that is produced. Some technologically-based investigations of tone production on the violin have recently been undertaken. Some of those appear to be based upon the theories put forth by the violin pedagogues cited above and also those of other pioneers.
Burton Kaplan was one such pioneer. In his U.S. Pat. No. 3,730,964, "Method and Apparatus for Instruction of Stringed Instrument Bow Positioning," which is incorporated by reference as if set forth fully here, Kaplan discussed how a bow position sensor that was secured to a stringed instrument and an indicator that responded to the sensor would provide an indication to the student of each departure of the bow from a desirable position. In another patent of his, U.S. Pat. No. 3,726,175, "Apparatus for Instruction of Stringed Instrument Positioning," Kaplan used an attitude sensor instead of a bow-position sensor. Both of these patents emphasized "bow position during play," which is the same as the "sounding point." It therefore seems likely that the "sounding point" is crucial, since Kaplan was a renowned violin teacher, and chose to focus his studies on the "sounding point."
Andre Askenfelt in 1986 also examined strategies for measuring scientifically the impact of these production parameters in a paper entitled "Measurement of bow motion and bow force in violin playing" in Journal of the Acoustical Society of America 80 (4) October 1986, which is incorporated by reference as if set forth fully here. In this work, three parameters characterizing bow control by a player under normal playing conditions were measured simultaneously by a piece of equipment. The method of measuring these three parameters is briefly described as follows.
Because of varying contact resistance, the precision of the measurements was low. When the bow was brought into contact with the strings in a sudden manner after it left the strings, some interfering signals were produced.
In summary, Burton Kaplan and Andre Askenfelt both examined aspects of violin tone production, but neither attempted to interpret the outcome, and neither stored or analyzed the interactive properties of the parameters.